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Are Rocks Friend or Foe?

When most people think of Rocks in their landscape, they typically think of the trouble they bring. Trying to dig a hole, put in a fence, or move a rock out of the way can all create issues for many.

I take a different approach.

I believe that Rocks of all shapes and sizes are extremely useful to us in Permaculture and they can be for you too.

Rocks or stones are naturally occurring solid masses of minerals or mineraloid matter. They are typically categorized by the minerals, chemical composition and the way it was formed. Rocks are made up of two or more minerals and can sometimes contain valuable minerals called Ore. Some rocks have literally remained unchanged for millions or tens of millions of years. We can quantify this by examining things like fossils from this time period.

There are several types of rocks-Igneous Rocks, Sedimentary Rocks, Limestone rocks, Shale, Sandstone, Conglomerate, Metamorphic Rocks, Marble, Slate, and Gneiss to name a few. The top three main types of rocks are Igneous, Sedimentary and Metamorphic.

Igneous Rocks are typically formed deep underground by molten rock. They are typically difficult to break as they are made up of crystalline (interlocking crystals). Igneous rocks are solid products made up of magma, lava or volcanic activity. They have a rough texture with large mineral grains. Igneous rocks that are formed on the surface are made up of very small grains and a fine texture. A few examples of Igneous rocks would be Basalt-used in railways and also pumice stones for your feet. Granite is another example of Igneous rocks that is common and has been used in construction for thousands of years. It is considered one of the strongest building materials.

Sedimentary Rocks are eroded from the natural elements in nature. They include things like wind, rain, sun, frost etc. When these forces take place, small sediment can be carried to new locations and settle. It continues to collect and become compacted by the pressure of the layers on top of it. There are three types of Sedimentary rocks-Clastic, Organic and Chemical.

-Clastic Sedimentary are formed from other pieces of rocks

-Organic Sedimentary are formed from materials such as plants, shells, bones

-Chemical Sedimentary are formed when a chemical compound such as

Calcium Carbonate is disolved in solution over time. The water eventually

evaporates and a sediment is left behind. Typically fossils can occur in these.

(Calcium Carbonate is the main component of Limestone. Limestone is often used

in Agriculture for neutralizing soils and in construction for concrete and steel.

Sandstone is another type of Sedimentary rock. It is considered compacted sand and there are many different types of this type of rock as it is formed from deposits from around the world.

Metamorphic Rocks are only formed underground. They are continually dragged below the surface due to movements of the lithosphere (the rigid outer part of the earth). In simple terms, underneath the earth's crust the temperature continues to rise as you go deeper. Due to this and the pressure of the earth around the rock, the rock changes. This process is called Metamorphism. This process continues to cause new minerals to grow and in some rocks with flat or elongated minerals the pressure will squeeze and stretch minerals in patterns or lines.

You will see Metamorphic rocks on the surface, but this is due to erosion, weathering, mountain building processes. They are not compressed above the surface of the earth, only appear there after events have brought them to the surface.

Marble is a good example of a Metamorphic rock. It is actually limestone that has undergone metamorphosis. Slate is another example of a metamorphic rock structure as is Gneiss which forms from shale.

A common misconception is that rocks start and end and part of this process is transformation from Igneous-sedimentary-metamorphic. This is not true. Any rock can transform into any rock in any direction.

How can these interesting and magnificently formed masses be useful for us on our land and in our lives. I have listed some below, but keep in mind that the list is not complete and can be added to at anytime.

  1. Borders- I love using them to make things like Rock Herb spirals, lining and defining areas and making pathways.

  2. Thermal Mass- Thermal mass is a way to passively heat and cool. It is the ability of a material to absorb, store and release heat. This helps to reduce the temperature fluctuations and moderate temps throughout the day/night. Rocks can be used for this purpose in cold frames, greenhouses, in landscape.

  3. Reclamation-With the right design, we can direct water flow in such a way that it does not erode or contribute to erosion. Rocks can be an integral piece in this plan. They can be used in Rock walls, retaining walls, terraces etc.

  4. Pathways-Stepping Stones or an accumulation of small stones to provide stability for the soil and create moisture barriers.

  5. Homes-Creating Habitats for animals, insects, snakes, lizards, toads, etc.

  6. Retention of moisture-Rocks are able to retain moisture due to its thermal mass attributes. If we design with this in mind, we can interplant trees, bushes and companion plants that will further expand the area around the Rock.

  7. Foundations and used for Fence posts-With the right planning, rocks can be used as a foundation for an outhouse or cabin and instead of concrete for fence posts.

  8. Drainage systems-Rocks can be used to slow down water and move water away from the feet of plants.

  9. Food-Rocks are food

for our trees and plants. Rocks were used as a primary source of food for trees and plants before synthetic fertilizers were introduced. They were crushed and spread throughout the area being planted or used in a solid mass state along the bottom of the garden.

  1. Ponds-Rocks can be used in both big and small ponds to retain water, protect the edging of the pond from erosion and provide a home for beneficial bacteria.

  2. Hold Water-using rocks in the bottoms of beds such as wicking beds, will help hold water

  3. Energetic Crystals-Some believe that certain types of rocks and crystals support healing physically and energetically. There is some evidence to support these claims.

No matter where you live in the world, we all need a little bit of help in some aspect of our landscape. So whether you own a large section or a small one, consider using rocks in your design elements, inside or outside.

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